I believe Sir Samual Baker used a 2bore Rifle in his expeditions in Africa, He also used a 4bore double, Squire Robin may be able to help me out here as Baker was a Brit, Anyway he wrote a book and in it he said he would set back to back with his tracker and at the shot it would spin them both compleatly around and give him (Baker) a headache the rest of the day. It shot either a 1/2 Lb. Ball or a hollowed ball charged with powder and fused. Baker said that Pachaderms when hit with the charged ball would stand for a few seconds then puff up and fall dead. Modern bullet designers still don,t get that kind of performance!